How to decide the parameters of GAMMA and NOISY_GAMMA ?

[Moon Moon]

Dear CP2K community,

I am doing AIMD using second-generation Car-Parrinello MD.

But I am confusing with the value of GAMMA and NOISY_GAMMA.

Reading related papers, they all said like the following:

So, I guess these two parameters should be revised in preliminary  run until the system temperature oscillates slightly around the target temperature, is it right ?

And I am also confused with the figure 1 in the paper "Effificient and Accurate Car-Parrinello-like Approach to Born-Oppenheimer Molecular Dynamics".  Why is the energy curve of SGCP so similar with that of BOMD, rather than oscillating arbitrarily near a certain horizontal line ?

Any comments will be appreciated, thank you.

[Thomas Kühne]

Dear Moon, 

in the 2nd image, the same trajectory is retraced. I.e. the trajectory is 1st recorded using SGCP and then retraced and the 

energy fully minimized. Also, be aware that this is the potential energy only and not the total energy. 

Wrt. how to adjust the parameters, one way is to scan different values for NOISY_GAMMA (= gamma_D of the paper) and 

then to overlay with a small conventional Langevin GAMMA to correct for remaining accuracies of the former. 

Best, 

Thomas Kühne

Am 07.01.2023 um 10:35 schrieb Moon Moon <yue...@gmail.com>:

Dear CP2K community,

I am doing AIMD using second-generation Car-Parrinello MD.

But I am confusing with the value of GAMMA and NOISY_GAMMA.

Reading related papers, they all said like the following:

<微信截图_20230107182222.png>

So, I guess these two parameters should be revised in preliminary  run until the system temperature oscillates slightly around the target temperature, is it right ?

And I am also confused with the figure 1 in the paper "Effificient and Accurate Car-Parrinello-like Approach to Born-Oppenheimer Molecular Dynamics".  Why is the energy curve of SGCP so similar with that of BOMD, rather than oscillating arbitrarily near a certain horizontal line ?

<QQ?????20230 107183132.png>

Any comments will be appreciated, thank you.

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<QQ?????20230 107183132.png><微信截图_20230107182222.png>

==============================

Thomas D. Kühne

Dynamics of Condensed Matter

Chair of Theoretical Chemistry

University of Paderborn

Warburger Str. 100

D-33098 Paderborn

Germany

thomas...@upb.de

+49/(0)5251/60-5726

[Moon Yue]

Dear  Kühne

Thank you for your kind reply.

Do you mean that corresponding BOMD values should be calculated for energy and force using the configurations produced and recorded using SGCP at different times ?

If doing in that way, Why is there continuous line of BOMD instead of dotted line ?

Best regards,

Yue